Kaskaskia, Illinois

Kaskaskia is a small incorporated village in the southwestern portion of Illinois. With a mere 21 residents as of the 2020 Census, it is the second-smallest incorporated community in the state.

In its heyday the village had around 7,000 residents and was originally the capital of Illinois Territory and, briefly, the first capital when Illinois became a state.

A port city at the confluence of the Mississippi and Kaskaskia Rivers, the city was virtually wiped out in April 1881 by flooding, which also created a geographical oddity: the Mississippi River changed course and now flows east of the village, thus making the village an exclave of Illinois accessible only via a small bridge over a bayou (which was the original Mississippi River channel, now mainly silted in) from Missouri (there is no highway access from Illinois). As such, it actually has a Missouri ZIP Code but an Illinois Area Code.